U.S. Pat. No. 3,248,004 issued Apr. 26, 1966 discloses a bottle carrier of the wraparound type in which locking tabs having heel and toe portions are foldably joined to an end edge of the wrapper blank and in which a plurality of cooperating apertures are formed in the blank adjacent the opposite end thereof. This type of lock is manipulated so as to insert the heel of the lock into the associated locking aperture and thereafter the toe portion of the lock is folded toward the lock and into interlocked relation therewith. This type of lock is satisfactory for some purposes but is objectionable in that the locks project from an end edge of the wrapper and hence constitute an element of cost and are also subject to inadvertent unlocking because the security of the lock depends primarily on the stiffness or fight in the locking toe whereby the toe portion is held in interlocked relation with its associated aperture.
U.S. Pat. No. 3,351,263 issued Nov. 7, 1967 discloses a panel interlocking means wherein a locking tab is struck from one panel and folded through one aperture in another panel to be interlocked and thence inserted subsequently through a second aperture formed in the other panel. While this type of locking arrangement provides an effective lock, manipulative operations necessary to form the lock are somewhat difficult to perform at high speed in high speed packaging machines.
British Pat. No. 1,436,166 published May 19, 1976 discloses a wrapper type package in which apertures are formed at one end of the blank and locking tabs project outwardly from the opposite end of the blank and slots formed near the base of the locking tabs receive shoulder portions of the locking tabs after they are inserted through the locking apertures during a package forming operation. This type of lock requires manipulative operations of substantial complexity.